Reversing linkage



REVERSING LINKAGE 2 S heetsSheet 1 FIG. I f

ATTORNEYS Dec. 8, 19,70 D. F. CHRISTOFFERSON' Filed Sept. 19, 1968 LAFlG.4

Dec; 8,1970 D. F. CHRISTOFFERSONJT 29 7 REVERSING LINKAGE j 7 Filed p 191968 2 Sheets-Sheet 2 iNVENTOR,

DONALD ECHRISTOFFERSQN ATTORNEYS United States Patent O 3,545,298REVERSIN G LINKAGE Donald F. Christoiferson, San Jose, Calif., assignorto FMC Corporation, San Jose, Calif., a corporation of Delaware FiledSept. 19, 1968, Ser. No. 760,907

Int. Cl. Gg 1/00 US. Cl. 74-469 11 Claims ABSTRACT on THE DISCLOSURE Amechanism having a pair of arms and a pair of links connecting anactuating shaft with a control rod so that rotation of the shaft in aclockwise direction causes the control rod to move longitudinallyoutward, while counterclockwise rotation of the shaft moves the controlrod longitudinally inward, and longitudinal movement of the shaftreverses the mechanism so that clockwise shaft rotation causes inwardcontrol rod movement, while counterclockwise shaft rotation results inoutward control rod movement.

BACKGROUND OF THE INVENTION Field of the invention This inventionrelates to a reversing mechanism and more particularly, to a mechanismfor translating rotary shaft movement into longitudinal control rodmovement that can be reversed upon longitudinal movement of the shaft.

Description of the prior art SUMMARY OF THE INVENTION An actuating shaftis connected by a first linkage to a control rod so that clockwiserotation of the shaft moves the control rod outward, whilecounterclockwise rotation of the shaft moves the control rod inward.Upon longitudinal movement of the shaft, the first linkage is disengagedand a second linkage is engaged so that clockwise rotation of the shaftmoves the control rod inward, while counterclockwise rotation of theshaft moves the control rod outward. This reversing mechanism enablesthe steering system of a track-type vehicle to steer the same way whenmoving in reverse as when moving forward.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a perspective view of areversing mechanism embodying the present invention.

FIG. 2 is a vertical section taken on the line 22 of FIG. 1 whereininternal parts are shown in side elevation.

FIG. 3 is a section taken on the line 33 of FIG. 2.

FIG. 4 is a section taken on the line 44 of FIG. 3.

FIG. 5 is an exploded perspective view of the actuating shaft, togetherwith the first and second linkage sleeves that are shown in FIG. 4.

DESCRIPTION OF THE PREFERRED EMBODIMENT Looking now at FIG. 1, areversing mechanism 10 is shown having an actuating shaft 12 with a bellcrank 14 clamped to one end of the shaft. The bell crank is used to turnthe shaft in a clockwise direction as indicated by the arrow 16 or in acounterclockwise direction as indicated by the arrow 18.

Positioned below the bell crank .14 is a support 20 through which theactuating shaft 12 passes and a packing 19 and a bearing 21 are fittedwithin the support around the actuating shaft. A linkage housing 22 iscoupled to the support by machine screws and encloses a portion of theactuating shaft below the support. The linkage housing has a hollow noseportion projecting outward perpendicular to the actuating shaft and thisportion of the linkage housing is provided with an upper access cover 24and a lower access cover 26, as shown in FIG. 2. Machine screws securethe access covers in place and the nose portion of the linkage housingterminates in a part ing flange 28 which is adapted to be bolted toadjoining structure, not shown.

An annular collar 30 fits within the center of the parting flange 28 andan O-ring packing 32 fits around the circumference of the collar andforms a seal between the collar and the linkage housing 22. A controlrod 34 is slidably fitted through an opening in the center of theannular collar and extends into the interior of the linkage housingwhere it terminates in a clevis portion 36. The control rod is adaptedto slide within the opening in the annular collar in an outwarddirection, as indicated by the arrow 38, or in an inward direction, asindicated by the arrow 39.

Within the linkage housing 22 is a washer 40 that fits about theactuating shaft 12 beneath the support 20. A first linkage 42 fits aboutthe actuating shaft below the washer and includes a sleeve 44 having anaxial opening 46, shown in FIG. 5, to receive the actuating shaft and agroove 48 that extends radially outward from the axial opening andtapers in width upwardly from the lower portion of the sleeve. An arm 50(FIGS. 2 and 3) projects radially outwardly from the lower portion ofthe sleeve and a link 51 is pivotably connected to the outer portion ofthe arm by a bolt 49 and a nut 47.

A washer 52 fits about the actuating shaft 12 below the first linkage 42and a second linkage 53 fits about the actuating shaft below the washer.The second linkage includes a sleeve 54 having an axial opening 56,shown in FIG. 5, to receive the shaft and a groove 58 that extendsradially outward from the axial opening and tapers in Width downwardlyto the lower portion of the sleeve. An arm 60 projects radially outwardfrom the upper portion of the sleeve 54 and a link 61 (FIGS. 2 and 3) ispivotably connected to the outer portion of the arm by a bolt 62 havinga nut 63. Ends of the links 51 and 61 opposite from the arms 50 and 60are connected to the clevis portion 36 of the control rod 34 by a pin 64that is held in place by a cotter pin 65.

A lug 66, as shown in FIG. 5, projects outwardly from the actuatingshaft 12 and tapers in circumferential width from a maximum at theapproximate mid-point MP of the lug, longitudinally along the shaft to aminimum at each end E of the lug. Thus, it will be seen that the upperportion of the lug is tapered to fit within the groove 48, while thelower portion of the lug is tapered to fit within the groove 58. Theactuating shaft is moveable longi tudinally in an upward direction, asindicated by arrow 67, and in a downward direction, as indicated by thearrow 69. The length L of the lug enables it to fit entirely within oneof the grooves so that when the lug engages one sleeve, the other sleevewill be disengaged.

At the lower portion of the linkage housing 22 is a hydraulic cylinder68 that moves the actuating shaft 12 longitudinally between an upperposition for lug 66 to engage sleeve 44 and a lower positionfor the lugto engage sleeve 54. The hydraulic cylinder includes an intermediatesupport 70, a body '72, and a cap 74 that are held in place by bolts 76extending through the cap and intermediate support into the linkagehousing.

A washer 77 fits around the actuating shaft 12 between sleeve 54 andintermediate support 70. A bearing 78 and a packing 79 are fitted aroundthe actuating shaft within the intermediate support and the center borewithin the support is stepped to form a guide seat 80 and a spring seat81. A fluid supply line fitting 82 is threadably fitted through theintermediate support from outside thereof to the center bore at alocation between the guide seat and the spring seat. A chamber 83 isformed within the body 72 and the actuating shaft extends through thischamber.

A helical compression spring 84 is fitted around a guide 85 that is heldin place near the end of the actuating shaft 12 between a stop 86 and ahydraulic piston 87. A seal 88 is fitted around the outer circumferenceof the hydraulic piston to contact the inner surface of the chamber 83.A guide 89 is held in place between the opposite side of the piston anda stop 90 that is secured on the end of the actuating shaft by a nut 92.A helical compression spring 91 fits around the guide 89 and seats upona spring seat 93 that is formed within the cap 74. A center bore furtherextends into the cap from the spring seat to a guide seat 94 and a fluidsupply line fitting 95 is threadably fitted through the cap from outsidethereof to the center bore, between the guide seat and the spring seat.A nut 96 holds the fluid supply line fitting in place on the cap and asimilar nut 97 holds the fluid supply line fitting 82 in place on theintermediate support 70. These nuts are secured by a wire 98 that passesthrough each nut and interlocks them together so as to prevent rotation.

In operation, the reversing mechanism can be installed in the steeringsystem of a track-type vehicle so that the operator controls the bellcrank 14 and the control rod 34 operates the steering system. Fluidsupply line fittings 82 and "95 are connected to a transmissionhydraulic system of the vehicle that causes forward and reverse clutchesto be engaged. When the vehicle is moving forward, hydraulic fluidforces piston 87 upward so that lug 66 fits entirely within the groove48 of sleeve 44. When bell crank 14 causes the actuating shaft 12 toturn in clockwise direction, the lug engages the sleeve and arm 50 turnsclockwise pulling link 51 and control 6 rod 34 inwardly, as indicated bythe arrow 39 in the FIG. 1. Since sleeve 54 is disengaged from the lug,arm 60 is free to rotate on the actuating shaft and inward movement ofthe control rod causes the link 61 to move the arm 60 in acounterclockwise direction. When the bell crank moves the actuatingshaft in a counterclockwise direction, arm 50 forces link 51 to move thecontrol rod 34 outward as indicated by the arrow 38.

When the vehicle is in reverse, the hydraulic system causes fluid toflow through the fitting 82 into chamber 83, forcing piston 87 into theposition as shown in FIG. 2. Lug 66 is then disengaged from sleeve 44and engages the sleeve 54 within the groove 58. Clockwise rotation ofthe actuating shaft 12 causes sleeve 54 to move clockwise and arm 60forces the link 61 to move control rod 34 in an outward direction, asindicated by the arrow 38 in FIG. 1. Counterclockwise rotation of theactuating shaft causes the arm 60 to draw the link 61 and the controlrod 34 inward, as indicated by the arrow 39. Actuating arm 50 and link51 move with the control rod since the sleeve 44 is disengaged.

From the above description, it will be seen that the reversing mechanism10 reverses the input forces to the control rod when the transmissionoutput of the vehicle is reversed. It should further be noted that thelug 66 is always contained within the mating grooves 48 and 58 so thatsteering control is never lost so long as the vehicle is either movingforward or in reverse. Shifting from forward to reverse while thesteering wheel is turned causes reversing rotation of the arms and bysliding on the helical tapered edges of the lug which mate with theedges of the grooves. Thus, the vehicle will turn back on the same trackas in making a forward turn without moving the steering wheel and thisenables the steering wheel to maintain control over the steering system.

When the vehicle is in neutral, the fluid pressure in the hydraulicsupply lines is equal and helical springs 84 and 91 force the piston 87into an intermediate position. The lug 66 moves into a position betweensleeve 44 and sleeve 54, as shown in FIG. 4. In this position, the lughas no effect upon the steering because rotational force in eitherdirection Would cause links 51 and 61 to act opposite to each other andthereby balance out any effect on the control rod 34.

Although the best mode contemplated for carrying out the presentinvention has been herein shown and described, it will be apparent thatmodification and variation may be made without departing from what isregarded to be subject matter of the invention as set forth in theamended claims.

Having completed a detailed description of the invention so that thoseskilled in the art could practice the same, I claim:

1. A reversing mechanism comprising an actuating shaft mounted forlongitudinal movement in upward and downward directions and forrotational movement about its longitudinal axis in clockwise andcounterclockwise directions; a control rod mounted perpendicular to theshaft for movement longitudinally in outward and inward directions; afirst linkage connected to the control rod and engageable with the shaftto move the control rod outward in response to clockwise rotation of theshaft and inward in response to the counterclockwise rotation of theshaft; a second linkage connected with the control rod and engageablewith the shaft to move the control rod outward in response tocounterclockwise rotation of the shaft and inward in response toclockwise rotation of the shaft; a lug projecting from the shaft toengage either said first or said second linkage; and means for movingthe shaft longitudinally to position the lug in engagement with eithersaid first or said second linkage.

2. A reversing mechanism as defined in claim 1 wherein said firstlinkage includes a sleeve having an axial opening to receive the shaftand a groove extending radially outward from the axial opening toreceive the lug on the shaft, an arm projecting radially outward fromthe sleeve, and a link pivotably connected to the arm and to the controlrod; and said second linkage includes a sleeve having an axial openingto receive the shaft and a groove extending radially outward from theaxial opening to receive the lug on the shaft, an arm projectingradially outward from the sleeve, and a link pivotably connected to thearm and to the control rod; said second linkage 'being spacedlongitudinally along the shaft from the first linkage.

3. A reversing mechanism as defined in claim 2 wherein the lug tapers inwidth from its approximate midpoint longitudinally along the shaft toopposite ends; and the grooves within each sleeve have their largestwidth dimension at the abutting ends of the sleeves and taper to theopposite ends thereof.

4. A reversing mechanism as defined in claim 3 wherein the means formoving the shaft axially include a hydraulic piston fitted about one endof the shaft and a hydraulic cylinder fitted about the hydraulic piston,a first hydraulic fluid supply line connected to the hydraulic cylinderon one side of the piston, and a second hydraulic fluid supply lineconnected to the hydraulic cylinder on the opposite side of the pistonfrom the first hydraulic fluid supply line, said hydraulic fluid supplylines being adapted to be connected to a hydraulic system that controlsthe hydraulic cylinder.

5. A reversing mechanism as defined in claim 2 wherein the arms of saidfirst and second linkages project outward toward opposite sides of thecontrol rod.

6. A reversing mechanism as defined in claim 5 wherein the arms of saidfirst and second linkages are of equal length and the links of saidfirst and second linkages are of equal length.

7. A reversing mechanism as defined in claim 6 wherein the links of saidfirst and second linkages are pivotably connected to the control rod ona common pivotal axis parallel with the actuating shaft.

8. A reversing mechanism comprising:

an actuating shaft mounted for rotational movement about itslongitudinal axis in clockwise and counterclockwise directions;

a control rod mounted perpendicular to the actuating shaft forlongitudinal movement inward and outward therefrom;

first means connected to the control rod and engageable with theactuating shaft for moving the control rod outward in response toclockwise rotation of the shaft and inward in response tocounterclockwise rotation of the shaft;

second means connected to the control rod and engagea'ble with theactuating shaft for moving the control rod outward in response tocounterclockwise rotation of the shaft and inward in response toclockwise rotation of the shaft; and

means for engaging the actuating shaft selectively with either saidfirst or second means connected to the control rod.

9. A reversing mechanism as described in claim 8 wherein said actuatingshaft is mounted for longitudinal movement and said means for engagingthe actuating shaft selectively with either said first or second meansconnected to the control rod is positioned for engagement bylongitudinal movement of the actuating shaft.

10. A reversing mechanism as described in claim 9 wherein said means forengaging the actuating shaft selectively with either said first orsecond means connected to the control rod can be positioned betweenengagement positions by longitudinal movement of the actuating shaft andin such intermediate position said mechanism is inoperative fortranslating rotational movement of the actuating shaft into longitudinalmovement of the control rod.

11. A reversing mechanism as described in claim 10 including hydraulicmeans responsive to fluid pressure in one direction for moving theactuating shaft to an engagement position with the first means connectedto the control rod and responsive to fluid pressure in an oppositedirection for moving the actuating shaft to an engagement position withthe second means connected to the control rod; and resilient means forpositioning the actuating shaft with the engaging means intermediatelyof engagement positions when fluid pressure in both direction isequalized.

References Cited UNITED STATES PATENTS 3,143,894 8/1964 Tennis 74105MILTON KAUFMAN, Primary Examiner US Cl. X.R.

